custom cht guage install.....and lights
 

installed a cht guage tonite, removed and disassembled my clock for the mount, gonna find a fuel guage at hershey to chop so there isn't a hole in the center of the glass.

plus after seeing all the added on oil pressure lights threads i went a slightly different route.
went to radio shack and got some high intensity leds and resistors, 2 red ones for oil pressure, 2 yellow ones for charge light (fan belt). i mounted these on the abs ring that flushes the guage inside the clock housing. i used high temp black hot glue to secure everything in place.
these leds are extremely bright, if you're sitting in the drivers seat these leds will get your attention.
here are some pics.
i also installed my shift light.

http://forums.pelicanparts.com/uploa...1081228368.jpg
http://forums.pelicanparts.com/uploa...1081228386.jpg
http://forums.pelicanparts.com/uploa...1081228399.jpg
http://forums.pelicanparts.com/uploa...1081228435.jpg

WOW

Im ducking ahead of time

But what are those gauges for?

I'm gonna guess seperate EGT for left and right cylinder bank, which leads me to my next question....where did you get that gauge and how much:D ?

the guage was loaned to me from roninlb, it is from a small aircraft, this guage will read the temp at the spark plug gasket on cylinders 2 & 5 :D
the led's are slaved off of the stock charge/oil pressure lights.
rons new guage is the cat's meow though.

I don't like the look of a 2 inch gauge in a 3 inch hole. I don't see why people keep doing it. ???

If I was buying a car with that, I'd tell the owner to get it out or find something that fits.

But that's just my opinion!!!

You have been very busy this winter. How do you set the shift rpm for the light. Are you autocrossing on Sunday in Hershey?

B,

Why are cyls. 2 & 5 used for the gauge? Are these the ones that typically run the hottest? I have a single VDO CHT gauge and I need to decide which spark plug to use for the sender ring.

Thanks!

Hi Kevin.
I always used 2 & 5 because is a kinda average between the hottest and coolest cyl.. actually the difference between the hottest and coldest is about 15deg.. that's 15deg max at 3.2k - 3.5k rpm in a stock '77 CIS at Hy speeds.
I would say that #6 runs the hottest.. but I have read that others found #3 to be the hottest.

very nice! can you get a bit more in detail about the install? How are the CHT sensors mounted? Do you just tighten them w/ the spark plug? Power source for the gauge? How about the wiring for the LEDs? Thanks.

Thanks Ron.

I figured 3 & 6 were the hot ones. 6 seems be the one that dumps a valve guide most frequently. Just thought i'd ask what 2 & 5 would indicate. Understood!

in cold weather starts 2 & 5 is a good indicator of how long it's taking to warm up.. and a pro said 2 & 5 were good indicators when adjusting carbs.

How many amps should the LEDs draw? Lemme see here. . .

85 targa used 4W bulb, 4W = 14V x Namps = .29 amps (290ma)

3.0V LED voltage = .29 amps x NResistance= 10.34 ohms

Radio shack doesn't list internal resistance for the LEDs in the forward direction? I can't figure out voltage drop from LED #1 to #2.

How did you figure it out?

LED's are usually rated at 20mA sustained with a max. of 40mA. Anything higher than that will destroy them instantly. Running them close to 40mA reduces their lifetime.

Assume an LED does not have any significant resistance in forward direction. It has a voltage drop of typically 2 Volts. If you put them in series you need to calculate with 14.4-2*2=10.4 volts to dimension your current limiter. It would come out to be 10.4V/0.02A = 520Ohm. Hence if you put 7 diodes in series you can run them without resistor. Their "wattage" is only around 20mA*2Volts - 40mW. They are so much more efficient unlike filament bulbs that produce 90% heat and 10% light.

Check this link out. It has some basic information about LED's and explaines the current limiting resistors. http://www.gilway.com/html/appl-ledlamps.htm

Ingo

Looks cool to me....nice job, Bell! :)

the 2" guage in the 3" hole left me the room i needed for the leds......

the 2 red bulbs (i'll get specs on the leds tonite)are in series with a 500ohm resistor, running them at 20ma, the +side is hooked to ignition at the stock bulb, the ground goes to the trigger side of the bulb.
same with the yellow leds.

the shift light has built in"rpm pills" supplied by autometer, (the yellow square thing attatched to the light housing.